1. Field of the Invention
The present invention relates to an organic white light emitting diode (OLED) and a method for manufacturing the same, and, more particularly, to a white OLED in which the structure and material of an emission layer are improved so that the emission efficiency and the life-span of the white OLED are increased.
2. Discussion of the Background
In general, an organic light emitting diode (OLED) may include a substrate, an anode, an organic layer including an emission layer, and a cathode. An OLED is a spontaneous emission display that generates light by combining electrons and holes in the emission layer. OLEDs are advantageous because they may be driven at a low voltage, may have a high response speed, and may have a wide viewing angle. OLEDs may be used in light and thin information display devices, such as mobile telephones, to display images with high picture quality.
OLEDs that effectively generate white light may be used for a wide variety of applications, such as backlights in LCD displays, internal lights of vehicles, and illuminators in offices. White light OLEDs may be used with primary color filters, such as red, blue, and green filters, in color flat panel displays.
According to a first OLED manufacturing method, the emission layer may be composed of multiple layers that emit red, blue, and green. However, it is difficult to form the multiple layers, and the thickness of the emission layer must be obtained through trial and error to achieve white light. Furthermore, without regulation, the color of the light may change significantly with changes in the voltage. Also, the stability of the white OLED may deteriorate so that the life-span of the white OLED is very short.
According to a second OLED manufacturing method, an emission layer host material is doped with, or mixed with, an organic light emitting pigment. The processes of the second method are simpler than the processes of the first method. However, in the second method, the thin film that emits white light must also be obtained through trial and error. Furthermore, it may be difficult to control the doping concentration during mass production because the doping concentration is very small. Also, the color may change in response to small changes in the concentration of the dopant.
Therefore, there remains a need for white OLEDs having excellent emission efficiency and long life-spans.